Jack.



F. E. PLACE &; M. L. JENKINS.

JACK.

APPLICATION FILED I'EB.11, 1908.

900,585, Patented Oct. 6, 1908.

A TTORNEYS umrEnsTAirEs PATENT OFFICE. FREDERICK E. PLACE, OF CHICAGO, AND MERRILL L. JENKINSgOFII ARVEY, ILLINOIS, ASSIGNORS TO BUDA FOUNDRY & MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS JACK.

Specification of Letters Patent.

Patented Oct. 6, 1908.

Application filed February 11, 1908. Serial No. 415,324.

To all whom it may concern:

Be it known that we, FREDERICK E. PLAoE and MERRILL L. JENKINS, citizens of the United States, residing at Chicago and Earvey, res ectively, in the county of Cook and State 0' Illinois, have invented certain new and useful Improvements in Jacks, of which the following is a specification.

This invention has reference to the provision of an improved form of stop mechanism for preventing a greater than normal movement of the jack arts and safeguard it against accidents suc as would occur in case the travel of the movable arts of the jack was permitted to go beyonc a certain limited oint.

The first of the objects of this present invention is to provide a stop device for the purpose indicated, which will be centralized, that is, which will not tend to move any portion of the movable parts of the jack to one side or the other, as is common with some of the stop devices in ordinary use, and which at the same time will be reliable and effective, and not so liable to derangement as certain other devices of this character heretofore pro osed.

he above, as well as such other objects as may hereinafter appear, we attain by means of the construction which we have illustrated in preferred form in the accompanying drawings, wherein- Figure 1 is a sectional view indicating a construction of jack with our improvement applied thereto, and

Figure 2 is a view mainly in side elevation, with a ,portion'of the parts shown in section, indicating the mechanism as in raised position.

Referring now more particularly to Figure 1 it willbe seen that in carrying out our invention we provide first a standard or supporting post 3 around which there is a shell 4 con-. structed to be raised and lowered by means of a screw shaft 5, working throu h a threaded nut 6, the upper parts of the evice being carried in the shell cap 7 as shown, and the screw shaft being provided With suitable actuating means, as a pair of bevel gears 8 indicated, all of which is in substantial accord with a form of jack commonly well known in the art for many years.

Upon the lower end of the screw shaft 5 we mount a stop collar 9 arranged as indicated in Figure 2, with preferably a threaded connection with the screw shaft 5, by means of a thread which is the reverse in direction of the thread on said screw shaft, so that whatever the direction of motion of the said screw shaft the stop collar 9 when brought in contact with the stop flange 10 which projects inwardly from the standard 3, will not have a tendency to loosen or unscrew. As a further protective measure a pin indicated at 1 1 may be employed, and as a means for inserting the device or securing ready access to the interior of the casing, we make the chamber 12 open at the bottom and close it by means of the closing plate 13 which is removably attached by cap screws 14, as shown in Figure 1.

The operation of this device is as follows. The parts having been put together as described and shown in the drawing, when the screw shaft is elevated in lifting the jack, its further movement will finally be arrested by contact of the stop collar 9 against the stop flange 10, and by virtue of the reversal of the direction of the threads, any further effort at movement in the way of turning by the screw shaft 5 will have a tendency to tighten up the stop collar 9 upon its thread rather than to loosen the same. It will further be apparent in operation of the mechanism that the strain will be a central one along the line of the screw shaft, and that there will be no disposition to tilt the upper member of the jack or shell 4 as where a lateral stop device such as is commonly used is employed, and the stop device will also have greater strength by virtue of the arrangement shown, than would be possible in the provision of a pawl mounted within the shell 4 and adapted to engage a groove or notch in the exterior surface of the post or standard 3, which is a characteristic of the prior art.

Having thus described our invention and illustrated its use, What we claim as new and In testimony whereof we have hereunder 10 desire to secure by Letters Patent, is the folsigned our names in the presence of the two lowmg: subscribed wltnesses.

A stop mechanism for jacks, comprising in combination a movable screw shaft, a stop FREDERICK E. PLACE.

flange, and a stop collar carried by said screw ME RRILL JENKLNS' shaft and secured by a thread the reverse of Witnesses: the thread on the screw shaft, substantially GEO. E. Brown,

as described. C. K. VVHITTINGTON. 

